I'm really liking our LifeVenture Voyager S2 – a bit pricey but might comfy, 12-month old daughter seems to really like it (not keen in getting in it, but once in and lifted onto shoulders she loves it).
Loads of adjustment – I've got a long back and my wife doesn't, but the backpack has a lot of adjustment so we both get a comfy carry out of it.
There are others in the range, but my wife fancied all the bells and whistles as they were included (and would have cost more to buy at a later stage)…so far everything has been used with great success.